U.S. patent number 6,872,105 [Application Number 10/411,190] was granted by the patent office on 2005-03-29 for watercraft having a jet propulsion system with improved efficiency.
This patent grant is currently assigned to Bombardier Recreational Products Inc.. Invention is credited to Patrice Dusablon, Bhaskar Marathe, Gilles Pesant.
United States Patent |
6,872,105 |
Dusablon , et al. |
March 29, 2005 |
Watercraft having a jet propulsion system with improved
efficiency
Abstract
A watercraft, equipped with a jet propulsion system with
improved efficiency of operation is disclosed. Structures are
disposed within a water passage of the jet propulsion system at a
position upstream of the jet propulsion unit that modulate the
amount of water that is allowed to pass through the water passage.
The structures can be a flexible fluid filled bag, an adjustable
ride plate, and an additional water passage. Each of the structures
allow a greater amount of water into the water passage during
acceleration than during constant speed travel of the
watercraft.
Inventors: |
Dusablon; Patrice (Palm Bay,
FL), Pesant; Gilles (Palm Bay, FL), Marathe; Bhaskar
(Wooster, OH) |
Assignee: |
Bombardier Recreational Products
Inc. (Valcourt, CA)
|
Family
ID: |
28794407 |
Appl.
No.: |
10/411,190 |
Filed: |
April 11, 2003 |
Current U.S.
Class: |
440/1; 440/38;
440/47 |
Current CPC
Class: |
B63H
11/103 (20130101) |
Current International
Class: |
B63H
11/103 (20060101); B63H 11/00 (20060101); B63H
021/22 () |
Field of
Search: |
;440/1,2,38,47
;114/287 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Avila; Stephen
Attorney, Agent or Firm: BRP Legal Services
Parent Case Text
This application relies for priority on U.S. Provisional Patent
Application Ser. No. 60/371,497, filed on Apr. 11, 2002, entitled
"WATERCRAFT HAVING A JET PROPULSION SYSTEM WITH IMPROVED
EFFICIENCY." The contents of that provisional patent application
are incorporated herein by reference.
Claims
What is claimed is:
1. A watercraft comprising: a hull having a bow and a stern; an
engine supported by the hull; a water passage in the hull having an
inlet at a position forward of the stern of the hull, an interior,
and an outlet at a position proximate to the stern of the hull; a
jet propulsion unit disposed in a portion of the water passage, the
jet propulsion unit being operatively connected to the engine; a
flexible barrier having a water contacting surface with a shape,
the flexible barrier disposed in the water passage upstream of the
jet propulsion unit; and a fluid disposed on one side of the
barrier such that the barrier separates the interior of the water
passage from the fluid, and wherein the barrier is movable with
respect to the water passage such that water flowing in the passage
changes the shape of the water contacting surface of the
barrier.
2. The watercraft of claim 1, wherein the water passage is formed
at least in part by the hull.
3. The watercraft of claim 1, wherein the jet propulsion unit
comprises a pump housing and an impeller disposed within the pump
housing.
4. The watercraft of claim 3, wherein the water passage upstream of
the jet propulsion unit comprises a water intake ramp, the water
intake ramp comprising at least an interior wall supported by the
hull, the fluid being disposed between the interior of the water
passage and the interior wall.
5. The watercraft of claim 4, wherein the flexible barrier
comprises a flexible bag containing fluid that is attached to the
interior wall of the water intake ramp.
6. The watercraft of claim 1, wherein the flexible barrier
comprises at least one fluid containing elongate bag, the fluid
containing elongate bag allowing fluid within to flow toward the
water passage inlet and away from the water passage inlet.
7. The watercraft of claim 6, further comprising a plurality of
generally parallel fluid containing elongate bags.
8. The watercraft of claim 7, wherein a first set of bags is placed
on a starboard side of the water passage and a second set of bags
is placed on a port side of the water passage.
9. A watercraft comprising: a hull having a bow and a stern; an
engine supported by the hull; a water passage having an inlet at a
position forward of the stern of the hull and an outlet at a
position proximate to the stern of the hull; a jet propulsion unit
disposed in a portion of the water passage, the jet propulsion unit
being operatively connected to the engine; and a ride plate having
a water contacting surface, the ride plate supported by the hull
proximate to the inlet, the entirety of the water contacting
surface of the ride plate being operatively moveable through a
predetermined range from at least a first position where the ride
plate portion is disposed behind the inlet and a second position
where the ride plate portion partially covers the inlet, such that
the position of the ride plate portion determines the size of the
inlet.
10. The watercraft of claim 9, wherein the ride plate portion is
the entire adjustable ride plate.
11. The watercraft of claim 9, wherein the jet propulsion unit
comprises a pump housing and an impeller disposed within the pump
housing.
12. The watercraft of claim 9, wherein the ride plate portion is
disposed in substantially the same plane as the portion of the hull
immediately proximate to the ride plate portion, and the ride plate
portion remains substantially disposed within the same plane
throughout its movement.
13. The watercraft of claim 9, further comprising an actuator
operatively connected to the ride plate portion to actuate movement
of the ride plate.
14. The watercraft of claim 13, further comprising an ECU in
communication with the actuator, the ECU being disposed to receive
a condition of the watercraft and to transmit a signal to the
actuator in response to the condition received by the ECU.
15. The watercraft of claim 14, wherein: the ECU communicates with
the actuator through an electrical connection; and the ECU is
disposed to receive a signal representative of the acceleration of
the watercraft.
16. The watercraft of claim 13, wherein the actuator mechanism is
electro-mechanical.
17. A watercraft comprising: a hull having a bow and a stern; an
engine supported by the hull; a primary water passage having an
inlet at a position forward of the stern of the hull and an outlet
at a position proximate to the stern of the hull; a jet propulsion
unit disposed in a portion of the primary water passage, the jet
propulsion unit being operatively connected to the engine; a
secondary water passage longitudinally aligned with the primary
water passage, the secondary water passage including a secondary
inlet and a secondary outlet through which water may flow from the
secondary water passage into the primary water passage; a valve
disposed adjacent to the secondary water passage that modulates the
flow of water from the secondary water passage into the primary
water passage, the valve being movable between at least a first
position and a second position; and an actuator operatively
connected to the valve to move the valve between the first and
second positions based on sensed conditions of the watercraft, the
actuator is operatively connected to a controller that controls
movement of the valve to open toward the first position when the
watercraft accelerates and to close toward the second position when
the watercraft is operated at a high speed.
18. The watercraft of claim 17, wherein the jet propulsion unit
comprises a pump housing and an impeller disposed within the pump
housing.
19. The watercraft of claim 17, wherein the secondary water passage
outlet is disposed rearwardly toward the stern relative to the
secondary water passage inlet.
20. The watercraft of claim 17, wherein the secondary water passage
is disposed forward of the primary water passage and extends
rearwardly to connect with the primary water passage.
21. The watercraft of claim 17, wherein the secondary water passage
is disposed rearward of the primary water passage and extends
rearwardly to connect with the primary water passage.
22. The watercraft of claim 17, wherein the valve comprises a
sliding gate.
23. The watercraft of claim 17, wherein the valve comprises a
pivoting plate.
24. The watercraft of claim 23, wherein the valve comprises a pair
of pivoting plates.
25. The watercraft of claim 17, wherein the controller controls the
actuator based at least in part on a pressure in the primary water
passage.
26. A watercraft comprising: a hull having a bow and a stern; an
engine supported by the hull; a primary water passage having an
inlet at a position forward of the stern of the hull and an outlet
at a position proximate to the stern of the hull; a jet propulsion
unit disposed in a portion of the primary water passage, the jet
propulsion unit being operatively connected to the engine; a
secondary water passage and a tertiary water passage each disposed
laterally adjacent to the primary water passage, the secondary
water passage including a secondary inlet and a secondary outlet
through which water may flow from the secondary water passage into
the primary water passage, and the tertiary water passage including
a tertiary inlet and a tertiary outlet through which water may flow
from the tertiary water passage into the primary water passage; a
valve disposed adjacent to each of the secondary water passage and
the tertiary water passage that modulates the flow of water from
the secondary water passage and the tertiary water passage into the
primary water passage, each valve being movable between at least an
open position and a closed position; an actuator connected to the
valves to move the valves between the open position and the closed
position based on sensed conditions of the watercraft; and a
controller operatively connected to the actuator that controls
movement of the valves to progressively open when the watercraft
accelerates and to progressively close when the watercraft is
operated at a high speed.
27. The watercraft of claim 26, wherein the secondary water passage
outlet and the tertiary water passage outlet are disposed at an
upper portion of the primary water passage.
28. The watercraft of claim 26, wherein the jet propulsion unit
includes an impeller and the secondary water passage outlet and the
tertiary water passage outlet are disposed upstream of the
impeller.
29. The watercraft of claim 26, wherein the secondary and tertiary
water passages are connected.
30. The watercraft of claim 26, wherein the secondary and tertiary
water passages are in the form of an arch that straddles the
primary water passage.
31. The watercraft of claim 26, wherein the actuator comprises a
first actuator connected to the valve adjacent to the secondary
water passage and a second actuator connected to the valve adjacent
to the tertiary water passage.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to jet powered watercraft, especially
personal watercraft ("PWC"). More specifically, the invention
concerns the jet propulsion system of the watercraft. In
particular, the invention is directed to the construction of a
water passage at a position upstream of a jet propulsion unit that
modulates the amount of water allowed to pass through the water
passage.
2. Description of Related Art
Jet powered watercraft have become very popular in recent years for
recreational use and for use as transportation in coastal
communities. Jet-propelled watercraft offer high performance,
improved acceleration and handling, and shallow-water operation.
Accordingly, PWCs, which typically employ jet propulsion units,
have become popular, especially in resort areas. As the use of PWCs
has increased, a desire for improved performance, including greater
operational efficiency, also has increased.
Typically, jet powered watercraft, such as PWCs, have a jet
propulsion system mounted within the hull that ingests water and
expels the water at a high velocity from the stern to propel the
watercraft. For directional control, a nozzle is generally provided
at the outlet of the jet pump to direct the flow of water in a
desired direction. In the conventional PWC, turning is achieved by
redirecting the flow of water from the nozzle.
In the typical arrangement for a jet propulsion unit, an engine
output shaft is rotationally coupled to a drive shaft. The drive
shaft extends into a water passage, which is defined by the hull of
the watercraft partially below the water line. The water passage
extends from a point forward of the rear of the watercraft to the
rear of that watercraft. An impeller is attached to the drive shaft
and is disposed within a pump housing portion of the water
passage.
FIG. 7 shows a prior art jet propulsion system 600 disposed within
the hull 612, of which only a portion is shown in broken lines. As
shown, an inlet grate 642 is disposed at an inlet 686 to an intake
ramp 688. The inlet grate 642 prevents large rocks, weeds, and
other debris from entering the water intake ramp 688 and passing
through the jet propulsion system 600. A pump support 650 or ride
shoe forms the bottom portion 692 of the water intake ramp 688. The
pump support 650 is coupled to the hull 612 within a tunnel 694
through fasteners and/or adhesives (not shown). The pump support
650 includes a main body portion 651 having a vertical attachment
surface 652, a forward attachment location 654 that is secured to a
ride plate 696, and a ramp portion 656. A passage (not shown)
extends through the main body portion 651 of the pump support 650.
The ramp portion 656 forms the bottom portion 692 of the water
intake ramp 688.
From the water intake ramp 688, water enters into a jet pump 660.
The jet pump 660 includes an impeller 670 and a stator 680. The
impeller includes blades 672 that extend from a center portion 674
that is coupled to an engine by one or more shafts 698, such as a
drive shaft and/or an impeller shaft. The rotation of the impeller
670 pressurizes the water, which then moves over the stator 680
that comprises a plurality of fixed stator blades 682. The role of
the stator blades 682 is to decrease the rotational motion of the
water so that almost all the energy given to the water is used for
thrust, as opposed to just swirling the water. As shown, the
impeller 670 and the stator 680 are both disposed within a jet
propulsion unit housing 690 or pump housing. However, it is also
known to position the stator 680 at a position outside of the
housing 690 at a position downstream of the housing 690. The
housing 690 includes a peripheral wall 691 which defines a passage
through which water passes. A forward end 692 of the housing
peripheral wall 691 is attached to the vertical attachment surface
654 or the pump support 650. The forward end 692 of the housing
peripheral wall 691 defines the inlet into the housing 690.
Once the water leaves the jet pump 660, it goes through a venturi
610. In this prior art jet propulsion unit 600, the venturi 610 is
disposed at the rearward end of the housing 690. Since the
venturi's exit diameter is smaller than its entrance diameter, the
water is accelerated further, thereby providing more thrust. As
shown, the venturi 610 is integrated into the housing 690 and
comprises the outlet from the housing 690.
A steering nozzle 602 is pivotally attached to the venturi 610 so
as to pivot about a vertical axis 604. The steering nozzle 602 is
operatively connected to a steering mechanism such as a steering
handlebar (see, e.g., the steering handlebar 74 shown in FIG. 1).
Rotation of the steering handlebar causes the steering nozzle 602
to pivot around the vertical axis 604, thereby directing the water
discharge to result in a change in the steering direction of the
watercraft.
A water passage 695, through which water passes from left to right,
is illustrated in FIG. 7. Moving from left to right in this
illustration, which is upstream to downstream, the water passage
695 is defined by the inlet 686, the water intake ramp 688, the
pump support passage 653, the jet pump 660, the venturi 610 and the
steering nozzle 602.
When the amount of water passing through the jet propulsion system
600 is not optimized, it is possible that cavitation may occur as a
result of operation of the impeller 670. Cavitation occurs when an
object, such as the impeller 670, moves through a fluid, such as
water, at a sufficient speed to cause the water to form pockets of
vapor. In other words, the impeller 670 can rotate so quickly that,
at the tips of the impeller blades 672, a sufficiently low pressure
region may be created that the water will flash into vapor,
creating small vapor bubbles. When the vapor bubbles collapse, the
shock of the collapse can degrade the impeller blades 672
(especially at the tips of the blades 672) by "eating away" at or
pitting the blades 672. In addition, cavitation also has the
undesired effect of producing noise and vibration that also degrade
the operational efficiency of the jet propulsion system 608. In
addition, noise and vibration increases the stress and wear and
tear on the impeller 670 and components attached thereto.
In addition, when the watercraft is accelerating from a standing
still or a low speed condition, the water drawn through the inlet
686 by the action of the pump 660 experiences a drop of static
pressure, which is a condition that promotes cavitation. This
undesirable drop of pressure can be minimized by increasing the
size of the inlet 686, thus optimizing the system for the
acceleration mode. Conversely, as the speed of the craft increases,
the static pressure in the inlet builds up which leads to a
condition that minimizes the formation of cavitation on bubbles in
the flow, thus improving the propulsive efficiency of the pump 660.
However, when the craft is traveling at high speed, the inlet
pressure typically reaches an unnecessarily high level, this being
a result of the relatively large inlet size chosen to accommodate
the constraints of the low speed acceleration mode. Since a large
inlet 686 cuts into the planing area of the hull thus increasing
the drag, an inlet 686 optimized for acceleration from low speed
will yield lower propulsive efficiency at high speed, while
conversely an inlet 686 optimized for high speed will result in
poor acceleration performance due to the occurrence of
cavitation.
In view of the foregoing, a need has developed for a watercraft
with a jet propulsion system that provides improved operational
efficiency. Specifically, a need has developed for a watercraft
design where the amount of water passing through the jet propulsion
system can be modulated.
Also, in view of the foregoing, especially in view of the current
trend to increase the operational power of boats and PWCs, a need
has developed for a watercraft where cavitation is minimized or
eliminated altogether.
These needs remain unaddressed by the prior art.
SUMMARY OF THE INVENTION
One aspect of embodiments of this invention is to provide a
watercraft with a jet propulsion system that operates with improved
operational efficiency.
Another aspect of the invention provides a watercraft with a jet
propulsion system that minimizes or eliminates the occurrence of
cavitation.
A further aspect of the present invention provides a structure
disposed at the inlet of the water passage through which the amount
of water passing through the jet propulsion system can be
modulated.
In particular, this invention is directed to a watercraft with a
hull having a bow and a stern. An engine is supported by the hull.
A water passage is formed at least in part by the hull and has an
inlet opening at a position forward of the stem of the hull, an
interior, and an outlet at a position proximate to the stern of the
hull. A jet propulsion unit is disposed in portion of the water
passage. The jet propulsion unit is operatively connected to the
engine. In one embodiment, a flexible barrier is disposed in the
water passage upstream of the jet propulsion unit and a fluid is
disposed on one side of the barrier such that the barrier separates
the interior of the water passage from the fluid. The barrier is
selectively movable with respect to the water passage.
In another embodiment, this invention is directed to a watercraft
having a hull with a bow and a stem, an engine supported by the
hull, a water passage having an inlet opening at a position forward
of the stem of the hull and an outlet at a position proximate to
the stem of the hull. A jet propulsion unit is disposed in a
portion of the water passage and is operatively connected to the
engine. A ride plate is disposed on the hull proximate to the
inlet. At least a portion of the ride plate is operatively moveable
through a predetermined range from at least a first position where
the ride plate portion is disposed behind the inlet and a second
position where the ride plate portion partially covers the inlet.
The position of the ride plate determines the size of the
inlet.
In a third embodiment, this invention is also directed to a
watercraft having a hull with a bow and a stem, an engine supported
by the hull, a primary water passage having an inlet opening at a
position forward of the stern of the hull and an outlet at a
position proximate to the stem of the hull. A jet propulsion unit
is disposed in a portion of the primary water passage and is
operatively connected to the engine. A secondary water passage
longitudinally aligned with the primary water passage includes an
inlet and an outlet through which water may flow from the secondary
water passage into the primary water passage. A valve is disposed
adjacent to the secondary water passage that modulates the flow of
water from the secondary water passage into the primary water
passage. The valve is movable from at least a first position and a
second position. An actuator is operatively connected to the valve
to move the valve between the first and second positions based on
sensed conditions of the watercraft.
In a fourth embodiment, this invention is also directed to a
watercraft having a hull with a bow and a stem, an engine supported
by the hull, a primary water passage having an inlet opening at a
position forward of the stern of the hull and an outlet at a
position proximate to the stem of the hull. A jet propulsion unit
is disposed in a portion of the primary water passage and is
operatively connected to the engine. A secondary water passage and
a tertiary water passage are each disposed laterally adjacent to
the primary water passage. The secondary water passage includes a
secondary inlet and a secondary outlet through which water may flow
from the secondary water passage into the primary water passage,
and the tertiary water passage includes a tertiary inlet and a
tertiary outlet through which water may flow from the tertiary
water passage into the primary water passage. A valve is disposed
adjacent to each of the secondary water passage and the tertiary
water passage that modulates the flow of water from the secondary
water passage and the tertiary water passage into the primary water
passage. Each valve is movable between at least an open position
and a closed position. An actuator is connected to the valves to
move the valves between the open position and the closed position
based on sensed conditions of the watercraft. A controller is
operatively connected to the actuator that controls movement of the
valves to progressively open when the watercraft accelerates and to
progressively close when the watercraft is operated at a high
speed.
Preferably, the watercraft is a personal watercraft (PWC). The PWC
can be a seated PWC or a stand-up PWC. Additionally, the watercraft
could be a jet boat or a sport boat. The invention is not limited
to watercraft and is applicable to various types of water-going
vessels with jet propulsion units.
These and other aspects of this invention will become apparent from
the disclosure that follows and the figures appended hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
An understanding of the various embodiments of the invention may be
gained by virtue of the following figures, of which like elements
in various figures will have common reference numbers, and
wherein:
FIG. 1 illustrates a side view of a watercraft in accordance with
an embodiment of the invention;
FIG. 2 is a top view of the watercraft of FIG. 1;
FIG. 3 is a front view of the watercraft of FIG. 1;
FIG. 4 is a rear view of the watercraft of FIG. 1;
FIG. 5 is a bottom view of the hull of the watercraft of FIG.
1;
FIG. 6 illustrates an alternative stand-up type watercraft;
FIG. 7 is a partial, cross-sectional side view of the stem of a
watercraft showing a prior art jet propulsion system;
FIG. 8 is an enlarged, partial, cross-sectional side view of the
stem of a watercraft showing a first embodiment of the jet
propulsion system of the present invention;
FIG. 9 is a bottom view of a portion of the jet propulsion system
of FIG. 8, showing the watercraft in a first condition;
FIG. 10 is a bottom view of a portion of the jet propulsion system
of FIG. 8, showing the watercraft in a second condition;
FIG. 11 is an enlarged, partial, cross-sectional side view of the
stem of the watercraft showing another embodiment of the jet
propulsion system of the present invention;
FIG. 12 is a bottom view of a portion of the jet propulsion system
of FIG. 11;
FIG. 13 is a bottom view of a portion of an alternative embodiment
to the jet propulsion system illustrated in FIG. 11;
FIG. 14 is a side view illustration of a further embodiment of a
watercraft of the present invention, with a portion of the hull
broken away to show part of the jet propulsion system;
FIG. 15 is a rear view of the watercraft of FIG. 13, with a portion
of the hull broken away to show part of the jet propulsion
system;
FIG. 16 is a bottom view of a portion of the jet propulsion system
of FIG. 13;
FIG. 17 is a side view illustration of another embodiment of the
watercraft of the present invention, with a portion of the hull
broken away to show part of the jet propulsion system;
FIG. 18 is a bottom view of the watercraft illustrated in FIG.
17;
FIG. 19 is a schematic side view in cross section of another
embodiment of the watercraft of the present invention; and
FIG. 20 is a schematic side view in cross section of the embodiment
of FIG. 19 shown in an open position.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)
While this invention is specifically directed to a PWC and the jet
propulsion system that powers such a watercraft, the invention is
not intended to be limited solely to a PWC. As would be appreciated
by those skilled in the art, the invention also encompasses other
types of watercraft, including boats of any kind having water jet
propulsion systems (e.g., sport boats, pontoon boats, yachts,
etc.)
The general construction of a personal watercraft 10 in accordance
with one embodiment of this invention is shown in FIGS. 1-5.
The watercraft 10 of FIG. 1 is made of two main parts, including a
hull 12 and a deck 14. The hull 12 buoyantly supports the
watercraft 10 in the water. The deck 14 is designed to accommodate
one rider and, in some watercraft, one or more passengers. The hull
12 and deck 14 are joined together in a sealing relationship at a
seam 16. Preferably, the seam 16 comprises a bond line formed by an
adhesive. Of course, other known joining methods could be used to
sealingly engage the parts together, including but not limited to
thermal fusion, molding, or fasteners, such as rivets or screws. A
bumper 18 generally covers the seam 16, which helps to prevent
damage to the outer surface of the watercraft 10 when the
watercraft 10 is docked, for example. The bumper 18 can extend
around the bow, as shown, or around any portion or all of the seam
16.
The space between the hull 12 and the deck 14 forms a volume
commonly referred to as the engine compartment 20 (shown in
phantom). Shown schematically in FIG. 1, the engine compartment 20
accommodates an engine 22, as well as a muffler, tuning pipe, gas
tank, electrical system (battery, electronic control unit, etc.),
air box, storage bins 24, 26, and other elements required or
desirable in the watercraft 10.
As seen in FIGS. 1 and 2, the deck 14 has a centrally positioned
straddle-type seat 28 positioned on top of a pedestal 30 to
accommodate a rider in a straddling position. The seat 28 may be
sized to accommodate a single rider or sized for multiple riders.
For example, as seen in FIG. 2, the seat 28 includes a first, front
seat portion 32 and a rear, raised seat portion 34 that
accommodates a passenger.
The seat 28 is preferably made as a single, cushioned or padded
unit. However, the seat 28 may be constructed as several separate
parts that interfit with one another. The first and second seat
portions 32, 34 are preferably removably attached to the pedestal
30 by a hook and tongue assembly (not shown) at the front of each
seat portion and by a latch assembly (not shown) at the rear of
each seat portion, or by any other known attachment mechanism.
Preferably, the seat portions 32, 34 can be individually,
completely removed. One of the seat portions 32, 34 covers an
engine access opening (in this case above engine 22) defined by a
top portion of the pedestal 30 to provide access to the engine 22
(FIG. 1). The other seat portion (in this case portion 34) can
cover a removable storage box 26 (FIG. 1). A "glove compartment" or
small storage box 36 may also be provided in front of the seat
28.
As seen in FIG. 4, a grab handle 38 may be provided between the
pedestal 30 and the rear of the seat 28 to provide a handle onto
which a passenger may hold. This arrangement is particularly
convenient for a passenger seated facing backwards for spotting a
water skier, for example. Beneath the handle 38, a tow hook 40
(FIG. 4) is mounted on the pedestal 30. The tow hook 40 can be used
for towing a skier or floatation device, such as an inflatable
water toy.
As best seen in FIGS. 2 and 4 the watercraft 10 has a pair of
generally upwardly extending walls located on either side of the
watercraft 10 known as gunwales or gunnels 42. The gunnels 42 help
to prevent the entry of water in the footrests 46 of the watercraft
10, provide lateral support for the rider's feet, and also provide
buoyancy when turning the watercraft 10, since personal watercraft
roll slightly when turning. Towards the rear of the watercraft 10,
the gunnels 42 extend inwardly to act as heel rests 44. Heel rests
44 allow a passenger riding the watercraft 10 facing towards the
rear to spot a water-skier, for example, to place his or her heels
on the heel rests 44, thereby providing a more stable riding
position. Heel rests 44 also could be formed as structures separate
from the gunnels 42.
Located on both sides of the watercraft 10, between the pedestal 30
and the gunnels 42 are a pair of footrests 46. The footrests 46 are
designed to accommodate a rider's feet in various riding positions.
To this effect, the footrests 46 each have a forward portion 48
angled such that the front portion of the forward portion 48
(toward the bow of the watercraft 10) is higher, relative to a
horizontal reference point, than the rear portion of the forward
portion 48. The remaining portions of the footrests 46 are
generally horizontal. Of course, any contour conducive to a
comfortable position for the rider could be used. The footrests 46
may be covered by carpeting 50 made of a rubber-type material, for
example, to provide additional comfort and traction for the feet of
the rider.
A reboarding platform 52 is provided at the rear of the watercraft
10 on the deck 14 to allow the rider or a passenger to easily
reboard the watercraft 10 from the water. Carpeting or some other
suitable covering may cover the reboarding platform 52. A
retractable ladder (not shown) may be affixed to the transom 54 to
facilitate boarding the watercraft 10 from the water.
Referring to the bow 56, as seen in FIGS. 2 and 3, the watercraft
10 is provided with a hood 58 and a helm assembly 60 located
forwardly of the seat 28. A hinge (not shown) is attached between a
forward portion of the hood 58 and the deck 14 to allow hood 58 to
be opened to provide access to the front storage bin 24 (FIG. 1). A
latch (not shown) located at a rearward portion of the hood 58
locks the hood 58 into a closed position. When in the closed
position, the hood 58 prevents water from entering the front
storage bin 24. Rearview mirrors 62 are positioned on either side
of the hood 58 to allow the rider to view objects behind the
watercraft 10.
A hook 64 is located at the bow 56 of the watercraft 10. The hook
64 is used to moor the watercraft 10 to a dock when the watercraft
is not in use. The hook 64 also functions as a convenient location
to attach a winch when loading the watercraft 10 onto a trailer,
for instance.
As best seen in FIGS. 3, 4, and 5, the hull 12 is provided with a
combination of strakes 66 and chines 68. A strake 66 is a
protruding portion of the hull 12. A chine 68 is the vertex formed
where two surfaces of the hull 12 meet. The combination of strakes
66 and chines 68 provides the watercraft 10 with its riding and
handling characteristics.
Sponsons 70 are located on both sides of the hull 12 near the
transom 54. The sponsons 70 preferably have an arcuate undersurface
that gives the watercraft 10 both lift while in motion and improved
turning characteristics. The sponsons 70 are preferably fixed to
the surface of the hull 12 and can be attached to the hull 12 by
fasteners or be molded integrally therewith. It is contemplated
that the position of the sponson 70 may be adjustable with respect
to the hull 12 to change the handling characteristics of the
watercraft 10 and accommodate different riding conditions.
As best seen in FIGS. 3 and 4, the helm assembly 60 is positioned
forwardly of the seat 28. The helm assembly 60 has a central helm
portion 72 that may be padded and a pair of steering handles 74,
also referred to as a handlebar. One of the steering handles 74 is
preferably provided with a throttle lever 76, which allows the
rider to control the speed of the watercraft 10.
As seen in FIG. 2, a display area or cluster 78 is located
forwardly of the helm assembly 60. The display cluster 78 can be of
any conventional display type, including LCD (liquid crystal
displays), dials or LED (light emitting diodes). The central helm
portion 72 may also have various buttons 80, which could
alternatively be in the form of levers or switches, that allow the
rider to modify the display data or mode (speed, engine rpm, time,
etc.) on the display cluster 78. The central helm portion 72 also
may be provided with one or more switches that change a condition
of the watercraft 10 such as trim (the pitch of the watercraft) to
modify the operational characteristics of the watercraft 10.
The helm assembly 60 may also be provided with a key receiving post
82, preferably located near a center of the central helm portion
72. The key receiving post 82 is adapted to receive a key (not
shown), that starts the watercraft 10. As is known, the key is
typically attaches to a safety lanyard (not shown), which clips
onto the operator's life vest or clothing. It should be noted that
the key receiving post 82 may be placed in any suitable location on
the watercraft 10.
Returning to FIGS. 1 and 5, the watercraft 10 is generally
propelled by a jet propulsion system 84, which includes a jet
propulsion unit or jet pump. The jet propulsion system 84 is shown
schematically in FIG. 1. As is known, the jet propulsion system 84
pressurizes water to create thrust. The water is first scooped from
under the hull 12 through an inlet 86, which preferably has a grate
(not shown in detail in FIGS. 1 and 5). Water flows from the inlet
86 through a water intake ramp 88. The top portion 90 of the water
intake ramp 88 is formed by the hull 12. A ride shoe (not shown in
detail in FIGS. 1 and 5) forms the bottom portion 92 of the water
intake ramp 88. Alternatively, the intake ramp 88 may be a single
piece or an insert to which the jet propulsion system 84 attaches.
In such cases, the intake ramp 88 and the jet propulsion system 84
are attached as a unit in a recess in the bottom of hull 12.
From the intake ramp 88, water enters the jet propulsion system 84.
The jet propulsion system 84 is located in a formation in the hull
12 referred to as the tunnel 94 (see FIG. 8). The tunnel 94 is
defined at the front, sides, and top by the hull 12 and is open at
the transom 54. The bottom of the tunnel 94 is closed by the ride
plate 96. The ride plate 96 creates a surface on which the
watercraft 10 rides or planes at high speeds.
The jet propulsion system 84 includes a jet propulsion unit or jet
pump 160 (seen in detail in FIG. 8, for example) made of two main
parts: the impeller and the stator. The impeller is coupled to the
engine 22 by one or more shafts 98, such as a drive shaft and/or an
impeller shaft. Alternatively, the one or more shafts 98 could be
operatively connected to one another through a gearbox or clutch.
The scope of the invention should not be limited to this type of
jet pump arrangement. Other jet pump arrangements are also
possible; for example, the jet pump 160 could have two
contra-rotating impellers.
The rotation of the impeller pressurizes the water, which then
moves over the stator that is made of a plurality of fixed stator
blades. The role of the stator blades is to decrease the rotational
motion of the water so that almost all the energy given to the
water is used for thrust, as opposed to swirling the water. Once
the water leaves the jet pump 160, it goes through a venturi 100.
Since the venturi's exit diameter is smaller than its entrance
diameter, the water is accelerated further, thereby providing more
thrust. A steering nozzle 102 is pivotally attached to the venturi
100 so as to pivot about a vertical axis 104. The steering nozzle
102 could also be supported at the exit of the tunnel 94 in other
ways without a direct connection to the venturi 100. Alternatively,
the nozzle 102 may be replaced by a rudder that re-directs the
pressurized water for steering.
The steering nozzle 102 is operatively connected to the helm
assembly 60 preferably via a push-pull cable (not shown) such that
when the helm assembly 60 is turned, the steering nozzle 102 pivots
about the vertical axis 104. This movement redirects the water
coming from the venturi 100, so as to steer the watercraft 10 in
the desired direction. Optionally, the steering nozzle 102 may be
gimbaled to allow it to move around a second horizontal pivot axis
(not shown). The up and down movement of the steering nozzle 102
around the horizontal pivot axis is known as "trim" and controls
the pitch of the watercraft 10.
When the watercraft 10 is moving, its speed is measured by a speed
sensor 106 (see FIG. 14) attached to the transom 54 of the
watercraft 10. The speed sensor 106 has a paddle wheel 108 that is
turned by the flow of water. In operation, as the watercraft 10
goes faster, the paddle wheel 108 also turns faster. An electronic
control unit (not shown) connected to the speed sensor 106 converts
the rotational speed of the paddle wheel 108 to the speed of the
watercraft 10 in kilometers or miles per hour, depending on the
rider's preference. The speed sensor 106 may also be placed in the
ride plate 96 or at any other suitable position. Other types of
speed sensors, such as pitot tubes, and processing units could be
used, as would be readily recognized by one of ordinary skill in
the art.
The watercraft 10 may be provided with the ability to move in a
reverse direction. With this option, a reverse gate 110, seen in
FIG. 4, is used. The reverse gate 110 is pivotally attached to the
sidewalls of the tunnel 94 or directly on the venturi 100 or the
steering nozzle 102. To cause the watercraft 102 move in a reverse
direction, the rider pulls on a reverse handle 112 (FIG. 1)
operatively connected to the reverse gate 110. The reverse gate 110
then pivots in front of the outlet of the steering nozzle 102 and
redirects the water leaving the jet propulsion system 84 towards
the front of the watercraft 10, thereby thrusting the watercraft 10
rearwardly. The reverse handle 112 can be located in any convenient
position near the operator, for example adjacent the seat 28 as
shown or on the helm 60.
Alternatively, this invention can be embodied in a stand-up type
personal watercraft 120, as seen in FIG. 6. Stand-up watercraft 120
are often used in racing competitions and are known for high
performance characteristics. Typically, such stand-up watercraft
120 have a lower center of gravity and a more concave hull 122. The
deck 124 may also have a lower profile. In this watercraft 120, the
seat is replaced with a standing platform 126. The operator stands
on the platform 126 between the gunnels 128 to operate the
watercraft. The steering assembly 130 is configured as a pivoting
handle pole 132 that tilts up from a pivot point 134 during
operation, as shown in FIG. 6. At rest, the handle pole 132 folds
downwardly against the deck 124 toward the standing platform 126.
Otherwise, the components and operation of the watercraft 120 are
similar to watercraft 10.
FIG. 8 shows a first preferred embodiment of the jet propulsion
system 84 of the present invention. As shown, the jet propulsion
system 84 is disposed within the hull 12, of which only a portion
is shown in broken lines to reveal the details of the jet
propulsion system 84.
As is shown in FIG. 8, the jet propulsion system 84 includes an
inlet 86 in the hull 12 that leads to a water intake ramp 88 in the
tunnel 94. An inlet grate 148 can be provided at the inlet 86. A
pump support 150 is secured within the tunnel 94. The water intake
ramp 88 is defined by an interior wall 89 and a ramp portion 156 of
the pump support 150. The jet pump 160 is secured within the tunnel
94 to the pump support 150.
According to one aspect of this invention, to control the volume of
water entering the jet pump 160, an elongate bag 202 containing
fluid is disposed within the water intake ramp 88. The bag 202 has
a first end 204 disposed proximate to the inlet 86 and a second end
206 disposed proximate to the jet pump 160. Specifically, the bag
202 is attached to the starboard side of the water intake ramp
interior wall 89, as seen in FIG. 8. The bag 202 in this embodiment
of the invention comprises a set of four generally parallel bags
212, 214, 216, and 218, which are shown being attached together in
a side by side arrangement. The four bags 212, 214, 216, and 218
could also be seen as four separate chambers of the elongate bag
202. Each of the four bags 212, 214, 216, and 218 preferably
extends from the first end 204 to the second end 206 and contain
fluid therein.
As would be appreciated by those skilled in the art, the bag 202
need not include only four bags 212, 214, 216, 218 to practice the
present invention. To the contrary, any number of bags equal to or
greater than one may be used to practice the present invention. In
addition, the bags 212, 214, 216, 218 need not be fluidically
separated from one another. Moreover, the bags 212, 214, 216, 218
need not be fluidically connected to one another. It is
contemplated that, where a plurality of bags are used, one or more
of the bags may be connected to others of the bags. In other words,
using the bag 202 as an example, bags 212 and 216 may be
fluidically connected while bags 214 and 218 are fluidically
distinct from one another and from bags 212, 216.
The bag 202 forms a flexible barrier which separates water in the
intake ramp 88 from the fluid in the bag 202. Specifically, the
fluid within the bag 202 is disposed between water in the intake
ramp 88 and a water intake ramp interior wall 89. Fluid within the
bag 202 is allowed to flow along its length, toward the water
passage inlet 86 and away from the water passage inlet 86. The flow
of fluid within the bag 202 toward the inlet 86 constricts the
inlet 86, and the flow of fluid within the bag 202 away from the
inlet 86 dilates the inlet 86.
FIG. 9 shows the bottom side of the watercraft 10. In this figure,
the inlet grate 148 has been removed so as not to conceal the
details of the invention. As is shown in this figure, the bag 202,
which is disposed on the starboard side of the water intake ramp
88, is accompanied by a second bag 220 disposed on the port side of
the water intake ramp 88. It is contemplated that the bags 202, 220
can be used together or separately. The first end 204 of the bag
202 and a first end 222 of the bag 220 are shown in their
respective positions within the water intake ramp 88. FIG. 9
further shows that the elongate bag 202 has an exterior surface 208
which is in contact with water in the water intake ramp 88, and an
interior surface 210 which is attached to the interior wall 89 of
the water intake ramp 88, through the use of fasteners (not shown)
or adhesives (not shown). Similarly, bag 220 has an exterior
surface 224 which is in contact with water in the water intake ramp
88, and an interior surface 226 which is attached to the interior
wall 89 of the water intake ramp 88.
FIG. 9 shows a first possible condition of the bags 202, 220, where
the fluid is evenly distributed.
FIG. 10 shows a second possible condition of the bags 202, 220,
where the fluid is being pushed rearwardly toward the jet pump
160.
The bags 202, 220 will assume whatever shape is optimal given the
momentary dynamic and static forces acting thereon during operation
of the watercraft 10.
Another aspect of this embodiment is providing a control mechanism
to control the flow of fluid in the bags, either manually or
automatically based on operating conditions of the watercraft 10.
In that case, a reservoir could be provided to allow fluid to flow
into or out of the bags. Such control could be hydraulic,
pneumatic, manual, or electronic, among others.
As would be apparent to one skilled in the art, a variety of fluids
(both liquids and gases) could be used within the bags 202, 220.
Fluids such as gels having a substantial viscosity could also be
used. Additionally, it would be apparent to one skilled in the art
that a single elongate bag can be used or that elongate bags that
do not have separated chambers can be used to practice the
invention. In the event that bags, which include separated
chambers, are used, it would be apparent to one skilled in the art
that the separate chambers could be disposed at any desired
orientation, such a horizontal.
In addition, while the foregoing description focuses on one
embodiment having two bags 202, 220 secured to the interior walls
89 at the sides of the water intake ramp 88, any other position of
the bag or bags within the water intake ramp 88 is considered to
fall within the scope of the invention. In particular, bags could
also be positioned at the top and bottom of the water intake ramp
88. In yet another alternative embodiment, a bag may partially or
wholly surround the inlet 86 to the water intake ramp 88. As would
be appreciated by those skilled in the art, the exact shape and
positioning of one or more bags within the water intake ramp 88 is
not critical to the practice of the present invention.
FIG. 11 shows another preferred embodiment of the jet propulsion
system 300 of the present invention. As shown, the jet propulsion
system 300 is disposed within the hull 12, of which only a portion
is shown in broken lines to reveal the details of the jet
propulsion system 300. An adjustable ride plate 302 is used to
modulate the amount of water entering through the inlet 86 into the
water intake ramp 88. The position of the ride plate 302 determines
the size of inlet 86.
Specifically, in this embodiment of the present invention, the
entire ride plate 302 preferably moves forward and rearward with
respect to the hull 12. As was previously described, the ride plate
302 provides a rigid surface disposed for contact with a body of
water while the watercraft 10 moves at high speeds. The ride plate
302 is movably mounted to a support plate 304 through the use of
linear bearings (not shown) or other known structure that allows
relative movement between two elements. The ride plate 302 has a
forward end 303, which is shown in a position immediately behind a
rearward portion 149 of the inlet grate 148.
An actuator 306 actuates movement of the ride plate 302 in relation
to the support plate 304. The actuator 306 in this embodiment
comprises an electric motor or other known electro-mechanic device
such as a solenoid. In the embodiment shown in FIG. 11, the
actuator 306 is mechanically connected to the ride plate through a
rack 310 and pinion 312 gear system. As would be apparent to one
skilled in the art, such a gear system is one of many ways that the
actuator 306 could transmit movement to the ride plate 302. Other
systems include an actuator comprising a linear stepper motor that
has a linear output shaft that pushes or pulls the ride plate 302
into a desired position. Hydraulic or pneumatic controls responsive
to manual input or automatically responsive to operating conditions
of the watercraft could also be used.
The actuator 306 is preferably electrically connected to an ECU
(shown schematically) or other known control unit through a known
electrical connection such as wire 308. The ECU is disposed to
receive a condition of the watercraft and to transmit a signal to
the actuator 306 in response to the condition received by the ECU.
The condition of the watercraft 10 can be acceleration, as measured
in a known manner through the monitoring of the throttle valve (not
shown), changes in the speed as measured by the speed sensor 106,
or changes in the pressure within the water passage 95 as measured
by a known pressure sensor 320. Upon the receipt of the signal at
the actuator 306, the actuator changes the position of the ride
plate 302, thus changing the size of the inlet 86.
As was previously shown in FIG. 4 with respect to the ride plate
96, the adjustable ride plate 302 also conforms to the bottom
surface of the hull 12. Specifically, the portions of the ride
plate 302 are preferably disposed in substantially the same plane
as the portions of the hull 12 immediately proximate thereto. The
various portions of the ride plate 302 remain substantially
disposed within the same plane throughout the movement of the ride
plate 302.
The ride plate 302 is operatively moveable through a predetermined
range from at least a first position where the ride plate 302 is
entirely disposed behind the inlet 86 to a second position where
the ride plate 302 partially covers the inlet 86. As is shown in
FIG. 11, when the ride plate 302 is in the second position, the
ride plate forward portion 303, which is shown in broken lines, is
beneath and partially overlaps the inlet grate 148. FIG. 12 shows
ride plate 302 in the first and second positions, with the second
position shown in broken lines.
When the watercraft 10 is operated at a constant high speed, the
ride plate 302 is maintained in the second position. In this second
ride plate position, the ride plate 302 partially closes the inlet
86. The amount of water necessary for the jet propulsion system 300
to generate sufficient thrust to maintain the constant speed is
provided by the inlet 86. However, when the watercraft 10 is
accelerated, particularly from a low speed condition, the ride
plate 302 is moved to the first position, thus reducing the water
pressure drop in the inlet 86. These improved flow conditions allow
the jet pump 160 to operate at a higher efficiency level, thus
generating a greater amount of thrust. Once the watercraft 10
reaches a higher speed, and a higher water pressure in the inlet
86, the ride plate 302 is moved back into the second position.
It should be noted that the ride plate 302 is not expected to have
only first and second positions (e.g., an open inlet 86 and a
partially-closed inlet 86). To the contrary, it is contemplated
that the position of the ride plate 302 may vary between the first
and second positions depending on the conditions input into the
ECU.
In addition, while the combination of an ECU and an actuator 306 is
contemplated in one embodiment of the invention, an
electromechanical operating system is not required to practice the
invention as would be appreciated by those skilled in the art,
other actuating systems may be employed.
For example, it is contemplated that the ride plate 302 may be
biased into an opened position by a spring or other suitable
biasing device. Movement of the ride plate 302 into a closed
position (e.g., where the ride plate 302 partially covers the inlet
86) could then be accomplished fluidically. In other words, the
increased pressure of the water in the water intake ramp 88 may be
used to push the ride plate 302 in the closed position. With such a
control system, when the watercraft 10 returns to a low-speed or
accelerating condition, the biasing spring would then cause the
ride plate to move into the partially-opened position.
In yet another embodiment, as illustrated in FIG. 13, it is
contemplated that only a portion 303 of the ride plate 305 will
move to partially close the inlet opening 86 during a steady state
operation. In this embodiment, the ride plate 305 remains fixed in
its position on the hull 12 of the watercraft 10. As a result, the
operational characteristics of the watercraft 10 will remain more
constant, despite the changing position of the ride plate portion
303. As would be appreciated by those skilled in the art, any type
of actuating device or system may be employed to move the ride
plate portion 303 during operation of the watercraft 10, including
those described above in connection with the ride plate 305.
In this regard, it is contemplated that a hydraulic piston could be
positioned between the ride plate 305 and the movable ride plate
portion 303 to move the ride plate portion 303 during operation of
the watercraft 10. If a hydraulic piston is employed, the piston
could be connected so that it utilizes the pressure of the water
within the water intake ramp 88 for operation.
FIG. 14 shows another preferred embodiment of the jet propulsion
system 400 of the present invention. As shown, the jet propulsion
system 400 is disposed within the hull 12, a portion of which is
broken away to reveal the details thereof. In this embodiment, the
primary water passage 95 is accompanied by at least a secondary
water passage 410 which has an inlet 412 that is independent of the
primary water passage inlet 86. A valve 420 regulates the amount of
water which may pass through the secondary water passage 410. The
secondary water passage 410 includes an outlet (elements 416 and
417 shown in FIG. 15) through which water in the secondary water
passage 410 is discharged into the primary water passage 95.
Accordingly, the secondary water passage 410 is used to modulate
the amount of water passing through the primary water passage
95.
FIG. 15 is a rear view with a portion of the transom 54 broken away
to reveal the jet propulsion system 400. The reverse bucket 110 has
also been removed from this figure. The secondary water passage 410
is preferably accompanied by a tertiary water passage 414, which,
as shown in FIG. 14, are preferably connected. Specifically, the
secondary and tertiary water passages 410, 414 are conduits in the
form of an arch which straddle the primary water passage 95.
Although secondary and tertiary water passages 410, 414 are shown,
it would be apparent that only one of the two water passages 410,
414 may be used. Alternatively, a greater amount of water passages
can also be used. It would also be apparent that the secondary and
tertiary water passages 410, 414 can be a unitary conduit
manufactured from metal, plastic or composite material, or an
assembly of fittings.
Outlets 416, 417 are provided, which comprise passages through
which water may flow from the secondary and tertiary water passages
410, 414 into the primary water passage 95. As would be appreciated
by one skilled in the art, the outlets 416, 417 can be openings in
the water passages 410, 414. Alternatively, the outlets 416, 417
can comprise fittings, valves, or other known devices or conduits
through which liquids may be moved. The outlets 416, 417 are
disposed at an upper portion of the primary water passage 95 at a
position upstream of the impeller within the jet propulsion unit
160. The outlets 416, 417 are also preferably disposed rearwardly,
toward the stern, relative to the secondary water passage inlet
412.
As shown in FIG. 16, the tertiary water passage 414 has an inlet
422 which, like the secondary water passage inlet 412, is disposed
laterally with respect to the primary water passage inlet 86.
Preferably, the inlets 412, 422 are formed directly in the hull 12.
The secondary water passage inlet 412 and tertiary water passage
inlet 422 are both also preferably disposed immediately proximate
to the primary water passage inlet 86. As is shown in FIGS. 14 and
16, the valve 420, which regulates the amount of water that may
pass through the secondary water passage 410, is disposed at the
secondary water passage inlet 412. A second valve 424, which
regulates the amount of water that may pass through the tertiary
water passage 420, is disposed at the tertiary water passage inlet
422. The valves 420, 424 modulate the flow of water from the
secondary and tertiary water passages 410, 414 into the primary
water passage 95. The valves 420, 424 are movable from at least a
closed position where no water passes though the secondary and
tertiary water passages 410, 414 to an open position where water
passes though the secondary and tertiary water passages 410,
414.
An actuator 426 actuates movement of the valves 420, 424. The
actuator 426 in this embodiment comprises an electric motor or
other known electro-mechanic device such as a solenoid. The
actuator 426 is mechanically connected to the valves 420, 424
through known mechanical elements such as levers or gears through
which the actuator 426 can transmit movement to the valves 420,
424. Other systems include an actuator comprising a linear stepper
motor that has a linear output shaft that pushes or pulls the
valves 420, 424 into a desired position. Of course, other known
actuators, such as hydraulic or pneumatic, may be used.
The actuator 426 is preferably electrically connected to an ECU
(not shown) or other known control unit through a known electrical
connection such as wire 427. The ECU is disposed to receive a
condition of the watercraft 10 and to transmit a signal to the
actuator 426 in response to the condition received by the ECU. The
condition of the watercraft 10 can be acceleration, as measured in
a known manner through the monitoring of the throttle valve (not
shown), changes in the speed as measured by the speed sensor 106,
or changes in the pressure within the water passage 95 as measured
by a known pressure sensor 320 (shown previously in FIG. 11). Upon
the receipt of the signal at the actuator 426, the actuator changes
the position of the valves 420, 424, thus changing the size of the
inlets 412, 422.
When the watercraft 10 is operated at a high speed, the valves 420,
424 are maintained in a closed or partially closed position.
However, when the watercraft 10 is accelerated from a low speed or
operates at a low speed, the valves 420, 424 are opened to minimize
the drop of water pressure in the inlet 86. This minimizes the
likeliness of cavitation to occur and allows the jet pump 160 to
operate more efficiently. When the watercraft 10 reaches a high
speed the valves 420, 424 are moved back into the closed or
partially closed position.
FIGS. 17 and 18 illustrate one further embodiment of the present
invention, jet propulsion system 500. Jet propulsion system 500 is
disposed within the hull, as shown in FIG. 17. Jet propulsion
system 500 is similar to jet propulsion system 400, except that the
secondary water passage 502 is positioned forwardly of the primary
water passage 95. A valve 504 regulates the amount of water passing
through the secondary water passage 502.
The secondary water passage 502 extends from a water inlet 506 to a
connective opening 508 with the primary water passage 95. As shown
in FIG. 17, the secondary water passage 502 is separated from the
primary water passage 95 by a wall 510 positioned at a forward end
of the inlet 86 in longitudinal alignment with the primary water
passage 95.
As in the previous embodiment, the valve 504 is essentially a
gate-like structure that can be slid or positioned over the inlet
506 into the secondary water passage 502. As the watercraft 10
accelerates from a low speed condition, the valve 504 is opened
progressively further to increase the total inlet area to minimize
the drop of water pressure in the inlet 86. When the watercraft 10
is moving at a high velocity, the valve 504 closes the inlet 506
into the secondary water passage 502 (partially or wholly) to
reduce the amount drag created by the water inlet 506.
As in the previous embodiment, the valve 504 may be controlled by
an actuator 510 connected to an ECU via a wire (or wing) 512. The
actuator 510 may be electrically, electromagnetically,
magnetically, hydraulically, or pneumatically controlled, among
others. The location of the valve 504 is illustrated in FIG.
18.
As would be appreciated by those skilled in the art, the secondary
and tertiary water passages 410, 414 could be used in combination
with the secondary water passage 502 to further increase the total
inlet cross-sectional area of the jet propulsion system, if
desired.
In both of the jet propulsion systems 400, 500, the secondary and
tertiary water passages 410, 414, 502 are angled upwardly and
rearwardly as illustrated in FIGS. 14 and 17. The slanted
arrangement of these water passages 410, 414, 502 assists in
directing additional water through the jet propulsion systems 400,
500. The upward and rearward slant helps to scoop water up into
water passages 410, 414, 502. As a result, the design of the water
passages 410, 414, 502 assists in improving the operation of the
jet propulsion systems 400, 500.
A similar embodiment is shown in FIGS. 19 and 20 in which the
secondary water passage is angled upward and rearward. In this
embodiment, the water intake ramp 88 leads to the primary water
passage 95 and a secondary water passage 550 is provided in the
rearward portion of the intake ramp 88 against a rear wall 552 of
the ramp 88. The secondary water passage 550 is longitudinally
aligned with the primary water passage 95 and has an inlet 554 and
an outlet 556 that feeds into the primary water passage 95. A
pivotal arcuate plate 558 is mounted across the intake ramp 88 to
either side of the hull 12. The plate 558 is curved forming an
inverted scoop. An actuating plate 560 is also pivotally mounted
across the intake ramp 88 below the arcuate plate 558. An actuator
562 is connected to the actuating plate 560 on either or both sides
in the hull 12 in a slot (not shown). The actuator 562 may be a
hydraulic piston as shown or any electrical or mechanical actuating
mechanism, including a gear or cable, for example.
In operation, the actuator 562 is connected to an ECU and may be
controlled as described above in the same manner as in the other
embodiments. As the watercraft 10 accelerates from a low speed
condition, the actuating plate 560, which functions as a valve, is
lifted progressively, which opens inlet 554 and then lifts arcuate
plate 558, which also functions as a valve to control the volume of
flow, to increase the total inlet area to minimize the drop of
water pressure in the inlet 86. When the watercraft 10 is moving at
a high velocity, the actuator 562 pushes the actuating plate 560
down to close the secondary water passage 550 (partially or wholly)
to reduce the amount of drag created by water inlet 86.
The embodiments described herein are not mutually exclusive and can
be used in combination. Additionally, as noted previously, this
invention is not limited to PWC's. For example, the jet propulsion
systems disclosed herein may also be useful in small boats or other
floatation devices other than those defined as personal
watercrafts. The adjustable inlets disclosed herein may be used in
any type of jet propulsion device.
Although the above description contains specific examples of the
present invention, these should not be construed as limiting the
scope of the invention but as merely providing illustrations of
some of the presently preferred embodiments of this invention.
Thus, the scope of the invention should be determined by the
appended claims and their legal equivalents rather than by the
examples given.
* * * * *